Well since I wrote the guide I got it there, I haven't played this game for a while but I seem to remember as I started to glide I jumped just as I left so that I went down a set of steps to gain a greater distance?
I think thats how I got it anyway!

The guide says the last glide ramp, which is after a missile door. The ramp goes up and has a small roof which I always land on (15 - 25m) if I do manage to clear this roof I get about 40 - 50m. Problem is I have tried here for so long, but directly in front is a bridge, so Im not even sure 100m is possible here! I have also tried ALL other glide ramps but they don't cut it at all.

When I glide I jump then put my arms out to my side, like the help says, but whereever I dive, and however I alter this, I simply nose dive to the floor, if I could somehow get some lift, it maybe help. Nitro does not seem to help.

I reckon I got it by pure luck! Like I said I found i got a greater lift and more of a float than a nosedive if I jumped just as I left the landing! try to keep your arms very high, at about 22 degrees to the horizontal rather than exactly horizontal if you know what I mean?